In my SkS & AK I have fired three types of 7.62X39 ammunition. Chinese copper coated steel cased, Wolf steel cased, and the last batch of Russian
that starts with "U" , I can't pronounce it, and no problems whatsoever.
I think those commie rifles were made to digest anything in the proper caliber without a hiccup...Of course the makers of our put together pieces of this and that don't have anything in mind sometimes but making something that will sell and don't actually test fire them to ascertain that they function properly..
It is said that Henderson Arms here in the US only sell arms that work properly and if I was going to get another SKS or AK47 I would definitly
check them out...